Light emitting apparatus and light unit having the same

ABSTRACT

Provides are a light emitting apparatus and a light unit having the same. The light emitting apparatus comprises a light emitting device comprising a light emitting element and a plurality of external leads, and a plurality of electrode pads under the light emitting device.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. 126 to KoreanPatent Application No. 10-2008-0011761 (filed on Feb. 5, 2007), which ishereby incorporated by reference in its entirety.

BACKGROUND

A light emitting diode (LED) constitutes a light emitting source byusing a compound semiconductor material, such as a GaAs-based compoundsemiconductor material, an AlGaAs-based compound semiconductor material,a GaN-based compound semiconductor material, an InGaN-based compoundsemiconductor material or an InGaAlP-based compound semiconductormaterial.

The LED is packaged and used as a light emitting device for emittinglight having various colors. Such an LED is used as a light source invarious fields, such as a lightening indicator for displaying colors, acharacter indicator, and an image indicator.

SUMMARY

Embodiments provide a light emitting apparatus comprising an improvedtilt between a light emitting device and a board, and a light unithaving the same.

Embodiments provide a light emitting apparatus, in which a leadelectrode of a light emitting device has the same shape as a pad of aboard, and a light unit having the same.

Embodiments provide a light emitting apparatus, in which a plurality oflight emitting devices are mounted on a flexible board with a stiffenerthereunder, and a light unit having the same.

An embodiment provides a light emitting apparatus comprising: a lightemitting device comprises a light emitting element and a plurality ofexternal leads; and a plurality of electrode pads under the lightemitting device.

An embodiment provides a light emitting apparatus comprising: aplurality of light emitting devices comprising a light emitting elementand a plurality of external leads; and a flexible board comprising aplurality of electrode pads thereon electrically connected to theexternal leads, and a stiffener thereunder.

An embodiment provides a light unit comprising: a plurality of lightemitting devices comprising a light emitting element and a plurality ofexternal leads; a board comprising a plurality of electrode padselectrically connected to the plurality of light emitting devices; and alight guide plate on one side of the light emitting device.

The details of one or more embodiments are set forth in the accompanyingdrawings and the description below. Other features will be apparent fromthe description and drawings, and from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side sectional view of a light emitting apparatus accordingto a first embodiment.

FIG. 2 is a projection plan view of a light emitting device on a boardin FIG. 1.

FIG. 3 is a side sectional view of the light emitting device in FIG. 1.

FIG. 4 is a front view of the light emitting device in FIG. 1.

FIG. 5 is a bottom view of the light emitting device in FIG. 1.

FIG. 6 is a plan view of the board in FIG. 1.

FIG. 7 is a detailed side sectional view of the board in FIG. 1.

FIG. 8 is a perspective view of a light unit according to a secondembodiment.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Hereinafter, a light emitting apparatus and a light unit having the sameaccording to embodiments will be described in detailed with reference tothe accompanying drawings.

FIG. 1 is a side sectional view of a light emitting apparatus accordingto a first embodiment, and FIG. 2 is a projection plan view of a lightemitting device on a board in FIG. 1.

Referring to FIGS. 1 and 2, the light emitting apparatus 160 comprises alight emitting device 100 and a board 140.

The light emitting device 100 comprises a light emitting diode (LED)chip 120 and a plurality of lead terminals 132 and 133. The lightemitting device 100 emits a color light, such as a red color, a greencolor and a blue color, or emits a white color.

At least one LED chip 120 may be arranged in each light emitting device.For example, the light emitting device may selectively comprise colorLED chips, such as a red LED chip, a blue LED chip, a green LED chip,and a yellow green LED chip.

First ends of the lead terminals 132 and 133 are electrically connectedto the LED chip 120, and external leads 134 and 135 being second ends ofthe lead terminals 132 and 133 are disposed under the light emittingdevice 100.

The board 140 comprises a flexible PCB (printed circuit board), and aplurality of electrode pads 114 and 145 are disposed over the board 140.The electrode pads 144 and 145 may be formed in the same shape as theexternal leads 134 and 135 of the light emitting device 100, and may belarger in size than the external leads 134 and 135 of the light emittingdevice 100. For example, both of the external leads 134 and 135 and theelectrode pads 144 and 145 may be formed in a circular shape, apolygonal shape, or a shape bent at a predetermined angle. The electrodepads 144 and 145 may be 1-1.5 times larger in size than the externalleads 134 and 135.

The plurality of light emitting devices 100 are arranged on the board140 in a predetermined direction, and the external leads 134 and 135 ofthe light emitting device 100 are electrically connected to theelectrode pads 144 and 145 on the board 140. The external leads 134 and135 of the light emitting device 100 are bonded to the electrode pads144 and 145 on the board 140 by solders through a surface mounttechnology (SMT) process. In this case, the external leads 134 and 135of the light emitting device 100 may be bonded within regions of theelectrode pads 144 and 145. Accordingly, since the light emitting device100 is arranged in parallel to the electrode pads 144 and 145 of theboard 140, the tilt problem of the light emitting device 100 can besolved.

A tilt value of the light emitting device 100 may be within ±0.2 mm withrespect to the top surface of the board 140.

FIG. 3 is a side sectional view of the light emitting device in FIG. 2,FIG. 4 is a front view of the light emitting device in FIG. 2, and FIG.5 is a bottom view of the light emitting device in FIG. 2.

Referring to FIGS. 3 and 4, the light emitting device 100 may beimplemented with a side view type package or a top view type package,and may be variously applied as a light source of an LCD device in aportable phone, a portable computer, etc., and a light emitting deviceof a lighting field. For convenience of explanation, the side view typepackage will be described as an example.

The light emitting device 100 comprises an LED chip 120, a package body110 with an opening 113, and a plurality of lead terminals 132 and 133.

The package body 110 may be formed of at least one of printed circuitboard (PCB), silicon, silicon carbide (SiC), aluminum nitride (AlN),poly phthalamide (PPA), and liquid crystal polymer, but the package body110 is not limited thereto.

Furthermore, the package body 110 may be injection molded with injectionmaterial, or may be formed using an etching process, or may be formed ofa PCB, but the package body 110 is not limited thereto. The injectionmaterial can form the package body in a desired shape by using press,for example, Cu/Ni/Ag alloy, and a material of structure of such aninjection material may be changed.

The opening 113 may be formed on one side of the package body 110. Theopening 113 serves to perform a reflection cup function and may beformed with a predetermined depth and in a predetermined shape. Acircumference surface of the opening 113 may be formed vertically orslopingly, but it is not limited thereto. Furthermore, according to thecurrent embodiment, the opening 113 may not be formed in the packagebody 110.

The plurality of lead terminals 132 and 133 are disposed in the packagebody 110 and may be implemented lead frames.

First ends 130 and 131 of the lead terminals 132 and 133 may be exposedto the opening 113 by passing through both sides of the package body110. The external leads 134 and 135 being second ends of the leadterminals 132 and 133 are disposed under the package body 110.Accordingly, the external leads 134 and 135 of the lead terminals 132and 133 may be disposed under the package body 110 through a formingprocess.

The first ends 130 and 131 of the lead terminals 132 and 133 areelectrically connected to the LED chip 120 within the opening 113. TheLED chip 120 and the first ends 130 and 131 of the lead terminals 132and 133 may be connected together by wires or may be connected togetherby die bonding or flip boding, but it is not limited thereto. The LEDchip 120 comprises a nitride semiconductor light emitting device.

The package body 110 may comprise semiconductor devices such as a lightreceiving device or a protecting device, but it is not limited thereto.The protecting device may be implemented with a Zener diode. The Zenerdiode protects the LED chip from electrostatic discharge (ESD).

A resin (not shown) is formed in the opening 113. The resin protects theLED chip 120 by using silicon or transparent resin such as epoxy. Atleast one kind of phosphor may be added to the resin, but it is notlimited thereto. The surface of the resin may be formed in a flat shape,a concave shape, or a convex shape, but it is not limited thereto.

Referring to FIGS. 4 and 5, the external leads 134 and 135 of the leadterminals 132 and 133 may be formed such that they are received ingrooves 119 formed on both bottom sides of the package body 110. Theexternal leads 134 and 135 are formed with a flat plate with apredetermined shape and it can improve adhesiveness of the solders inthe SMT process.

Referring to FIG. 5, the external leads 134 and 135 may be formed in acircular shape, an elliptical shape, a polygonal shape, or a shape inwhich some portions of the external leads 134 and 135 are cut or bent ata predetermined angle. As an example, the external leads 134 and 135 maybe formed in a shape in which their inner sides 134A and 135A extend ina rear surface direction of the package body 110 with respect to theforming direction, for example, a “

” shape.

FIG. 6 is a plan view of the board in FIG. 1.

Referring to FIG. 6, a plurality of electrode pads 144 and 145 aredisposed on the board 140. The electrode pads 144 and 145 may be formedin the same shape as the external leads (134 and 135 in FIG. 5). Theelectrode pads 144 and 145 may be formed in a circular shape, anelliptical shape, a polygonal shape, or a shape bent at a predeterminedangle. As an example, the electrode pads 144 and 145 may be formed in ashape in which their inner sides 144A and 145A protrude from arectangular shape, for example, a “

” shape.

Referring to FIGS. 5 and 6, the side lengths D5, D6, D7 and D8 of theelectrode pads 144 and 145 may be equal to or greater than the sidelengths D1, D2, D3 and D4 of the external leads 134 and 135. Herein, theside lengths D5, D6, D7 and D8 of the electrode pads 144 and 145 are1-1.5 times longer than the side lengths D1, D2, D3 and D4 of theexternal leads 134 and 135. The opposite sides D1 and D5, D2 and D6, D3and D7, D4 and D8 are formed to correspond to each other in the sameshapes.

Furthermore, the plurality of electrode pads 144 and 145 have a shapesymmetrical to one another, and the inner regions may be larger than theouter regions. Moreover, the plurality of external leads 134 and 135 maybe formed with sizes of the corresponding regions at the correspondingpositions of the electrode pads 144 and 145.

The electrode pads 144 and 145 may be larger in size than the externalleads 134 and 135. For example, the electrode pads 144 and 145 may be1-1.5 times larger in size than the external leads 134 and 135.

Since the entire regions of the external leads 134 and 135 of the lightemitting device 100 are contacted within the electrode pads 144 and 145of the board 140, it is possible to prevent the inclination of thecenter of gravity applied to both sides of the light emitting device100.

Furthermore, the electrode pads 144 and 145 of the board 140 can solvethe tilt problem of the dispensed solder thereon, and can also solve theheat dissipation problem through the uniform contact with the externalleads 134 and 135.

FIG. 7 is a detailed side sectional view of the board in FIG. 1.

Referring to FIG. 7, the board 140 is a double side flexible circuitboard and comprises a base film 141, first and second copper foil layers142 and 143, first and second adhesive layers 145 and 146, first andsecond coverlay layers 147 and 148, an insulating ink layer 149, astiffener 150, and a solder resist 153.

The base film 141 may comprise a polyimide film, and the first andsecond copper foil layers 142 and 143 are attached to both sides of thebase film 141 by using a base adhesive.

Predetermined circuit patterns may be formed in the first copper foillayer 142 and/or the second copper foil layer 143 and may be connectedtogether through interface such as vias, via holes, or through-holes.

A plating layer (not shown) may be formed on/under the first and secondcopper foil layers 142 and 143. A gold plating layer (not shown) may beformed in an opened region 152 of the first copper foil layer 142 by anelectroless plating process in order to protect the circuit patterns andprevent their oxidation. A copper plating layer may be formed in regionsother than the opened region.

The opened region 152 of the first copper foil layer 142 serves as theelectrode pads 144 and 145. The first coverlay layer 147 is attached tothe top of the first coil layer 152A by using the first adhesive layer145, and the insulating ink layer 149 is formed on the first coverlaylayer 147.

The insulating ink layer 149 is coated using a permanent ink (photosolder resist ink (PSR)) which is a permanent compound having durabilityin physical and chemical environments. Accordingly, the insulating inklayer 149 can protect the circuits and prevent the solder overlappingphenomenon between the circuits during the mounting of parts.

The second coverlay layer 148 is attached to the bottom of the secondcopper foil layer 143 by using the second adhesive layer 146, and thestiffener 150 is attached to the bottom of the second coverlay layer148.

The first coverlay layer 147 and the second coverlay layer 148 may beformed of polyimide. The stiffener 150 may be implemented with apolyimide film, and it reinforces the stiffness of the board 140 andprevents the bending thereof. The stiffener 150 prevents the tilt causedby the light emitting device (100 in FIG. 1) mounted by an SMT process.

On the top of the board 140, a portion of the first copper foil layer142 is opened to expose the electrode pads 144 and 145. A solder resist153 may be coated in an entire or partial surrounding of the openedregion of the first copper foil layer 142. Herein, after the lightemitting device 100 is mounted on the electrode pads 144 and 145, thesolder resist 153 prevents the contamination of the mounted region andreduces the tilt of the mounted light emitting device. The thickness orheight of such a solder resist 153 may be changed.

Although the board 140 has been described with reference to thesingle-side exposed structure of the electrode pads 144 and 145, it canalso be implemented with a double-side exposed structure. Furthermore,the board 140 may be changed within the technical scope of theembodiments.

FIG. 8 is a perspective view of a display device according to a secondembodiment.

Referring to FIG. 8, the display device 170 comprises a light emittingapparatus 160, a light guide plate 173, a reflection plate 171, anoptical sheet 175, and a display panel 177. The light emitting apparatus160, the light guide plate 173, the reflection plate 171, and theoptical sheet 175 may be defined as a light unit.

The light emitting apparatus 160 comprises a plurality of light emittingdevices 100 on a board 140 and is disposed in one side of the lightguide plate 173. The light emitting apparatus 160 may be disposed oneither or both sides of the light guide plate 173, but it is not limitedthereto.

The light emitting apparatus 160 comprises the light emitting devices100 and the board 140 and emits color lights, such as a red color, agreen color and a blue color, or emits a white color.

The board 140 may be implemented with a flexible board, and electrodepads 144 and 145 have the same shapes as the lead terminals (134 and 135in FIG. 1) with the larger sizes.

Therefore, the light emitting devices 100 mounted on the board 140 isnot almost tilted. Furthermore, the stiffener (150 in FIG. 7) of theboard 140 supports the board 140 in order not to be tilted in any onedirection when boding the light emitting device 100. Thus, it ispossible to prevent the tilt problem of the light emitting device 100and improve the electrical reliability of the light emitting device 100.

The light guide plate 173 serves as a light guide panel (LGP). The lightguide plate 173 may comprise reflection patterns on the rear surfacethereof, but it is not limited thereto. The light guide plate 173 guideslight incident from the light emitting apparatus 160, and reflects theguided light toward the panel direction. In this case, the surface lightis irradiated onto the light guide plate 173.

The tilt problem of the light emitting devices 100 in the light emittingapparatus 160 can be solved. In this case, it is possible to prevent thelight leakage phenomenon that some of the light emitted from the lightemitting device 100 leaks out. Furthermore, it is possible to solve theproblem that a portion of the light guide plate 173 becomes dark.

The reflection plate 171 may be disposed on the rear surface of thelight guide plate 173, or may be disposed on the rear surface of thelight guide plate 173 and a side where no light is incident.

The reflection plate 171 reflects light leaking downward through thelight guide plate 173 toward the direction of the panel.

At least one optical sheet 175 may be disposed on the light guide plate173 and may comprise a diffusion sheet, a prism sheet, and a brightnessenhancement sheet. The diffusion sheet is disposed on the light guideplate 173 to diffuse the incident light. The prism sheet may comprise ahorizontal prism sheet and/or a vertical prism sheet, and a brightnessenhancement sheet. The prism sheet condenses the light diffused by thediffusion sheet toward a light emission region.

The display panel 177 is disposed on the optical sheet 175 to displayinformation according to the light irradiated from the light unit. Apolarizer may be attached to the display panel 177, but it is notlimited thereto.

In the description of the embodiments, it will be understood that when alayer (or film), region, pattern or component is referred to as being‘on’ or ‘under’ another layer (or film), region, or patterns, theterminology of ‘on’ and ‘under’ comprises both the meanings of‘directly’ and ‘indirectly’.

Any reference in this specification to “one embodiment,” “anembodiment,” “example embodiment,” etc., means that a particularfeature, structure, or characteristic described in connection with theembodiment is comprised in at least one embodiment of the invention. Theappearances of such phrases in various places in the specification arenot necessarily all referring to the same embodiment. Further, when aparticular feature, structure, or characteristic is described inconnection with any embodiment, it is submitted that it is within thepurview of one skilled in the art to effect such feature, structure, orcharacteristic in connection with other ones of the embodiments.

Although embodiments have been described with reference to a number ofillustrative embodiments thereof, it should be understood that numerousother modifications and embodiments can be devised by those skilled inthe art that will fall within the spirit and scope of the principles ofthis disclosure. More particularly, various variations and modificationsare possible in the component parts and/or arrangements of the subjectcombination arrangement within the scope of the disclosure, the drawingsand the appended claims. In addition to variations and modifications inthe component parts and/or arrangements, alternative uses will also beapparent to those skilled in the art.

1. A light emitting apparatus, comprising: a light emitting device comprises a light emitting element and a plurality of external leads; and a plurality of electrode pads under the light emitting device, wherein the light emitting device comprises: a package body; a lead terminal comprising the external lead; and an opening on one side of the package body and in which one end of the lead terminal and the light emitting element are disposed.
 2. The light emitting apparatus according to claim 1, wherein the external leads have any one of a circular shape, a polygonal shape, and a shape in which a portion thereof is bent at a predetermined angle.
 3. The light emitting apparatus according to claim 1, wherein the electrode pads have the same shape as the external leads.
 4. The light emitting apparatus according to claim 1, wherein the board comprises a flexible board.
 5. The light emitting apparatus according to claim 4, wherein the flexible board comprises a stiffener thereunder.
 6. The light emitting apparatus according to claim 1, wherein the board comprises: a base film; a first copper foil layer on one side of the base film, a portion of the first copper foil layer being opened; a second copper foil layer on the other end of the base film; a first coverlay film on one side of the first copper foil layer; and a second coverlay film under the second copper foil layer.
 7. The light emitting apparatus according to claim 5, wherein the stiffener comprises a polyimide film.
 8. The light emitting apparatus according to claim 1, wherein the electrode pad of the board is larger in size than the external lead of the light emitting device.
 9. A light emitting apparatus, comprising: a plurality of light emitting devices comprising a light emitting element and a plurality of external leads; and a flexible board comprising a plurality of electrode pads thereon electrically connected to the external leads, and a stiffener thereunder.
 10. The light emitting apparatus according to claim 9, wherein the electrode pads are 1-1.5 times larger in size than the external leads.
 11. The light emitting apparatus according to claim 9, wherein the plurality of electrode pads have a shape symmetrical to one another, and have an inner region wider than an outer region.
 12. The light emitting apparatus according to claim 9, wherein a tilt value of the light emitting device with respect to the board is within ±0.2 mm.
 13. The light emitting apparatus according to claim 9, wherein the electrode pads have any one of a circular shape, a polygonal shape, and a shape in which a portion thereof is bent at a predetermined angle.
 14. The light emitting apparatus according to claim 9, wherein the light emitting device comprises: a lead terminal comprising the external lead; and a package body in which one end of the lead terminal is disposed; and a light emitting diode (LED) chip being a light emitting element electrically connected to one end of the lead terminal.
 15. A light unit, comprising: a plurality of light emitting devices comprising a light emitting element and a plurality of external leads; a board comprising a plurality of electrode pads electrically connected to the plurality of light emitting devices; and a light guide plate on one side of the light emitting device, wherein the light emitting device comprises: a package body; a lead terminal comprising the external lead; and an opening on one side of the package body and in which one end of the lead terminal and the light emitting element are disposed.
 16. The light unit according to claim 15, wherein the board is a flexible board comprising a stiffener thereunder.
 17. The light unit according to claim 15, wherein the plurality of pads on the board have a shape symmetrical to one another and are 1-1.5 times larger in size than the external leads of the light emitting device.
 18. The light unit according to claim 15, comprising: at least one optical sheet on the light guide plate; and a reflection plate under the light guide plate.
 19. The light unit according to claim 15, wherein a tilt value of the light emitting device with respect to the board is within ±0.2 mm. 